Since a teenage runaway turned belly dancer announced last week she had attended parties at Silvio Berlusconi's Milan home a new phrase has entered Italian life: Bunga bunga.

The phrase "bunga-bunga" has been dominating news bulletins, appearing in newspaper cartoons, rap songs and parodies on television shows and providing endless material for discussion among Italians in cafes and bars.

While some Italians are outraged that Mr Berlusconi allegedly ordered police to drop theft charges against Miss Keyek, also known by her stage name of Ruby, others have delighted in satirising the alleged "bunga-bunga" parties.

The phrase is said to come either from the punch-line to one of the premier's favourite bawdy jokes, or refers to an "erotic ritual" that Mr Berlusconi learned from his friend Muammar Gaddafi, the Libyan leader.

It has entered the Italian lexicon and inspired dozens of spoofs, including a rap song and a parody by a TV comedian in which the words to the Shakira hit 'Waka Waka' – the official theme tune for this year's Soccer World Cup - were replaced by references to bunga bunga.

An opposition party, Italy of Values, has come up with a campaign poster entitled "Evolution of the species?" with three images of Mr Berlusconi.

In the first, he is soberly dressed in a dark suit.

The second shows a photograph from 2004, when the permatanned Mr Berlusconi notoriously wore a bandana to cover his hair transplant, above the word 'papi' or 'Daddy' – the term of endearment reportedly used by the innumerable showgirls and models in his inner circle.

In the third he is dressed in the sort of traditional North African robes worn by Col Gaddaffi, above the words "bunga-bunga".

The catchphrase has even been co-opted by the sports press. When AC Milan, the team owned by Mr Berlusconi, were beaten at the weekend 2-1 by Juventus, La Gazzetta Sportiva ran the front page headline: "Bunga Bunga Juve!"